The present invention relates to the decontamination arts. It finds particular application in conjunction with the deactivation of biological agents and/or chemical agents in large convoluted spaces, such as public buildings.
Heretofore, gaseous sterilants, such as hydrogen peroxide vapor, have been used to sterilize the contents of sterilization chambers, the inside of isolators, or other relatively small spaces. The gaseous sterilant was typically generated external of the chamber and flowed through it either in either a closed loop or open loop system. To be sure that sterilization was achieved, chemical and biological indicators were positioned in with the sterilized items, or in corners or other areas where diminished flow of the sterilant vapor might be expected. The chemical indicators were then visually inspected to provide substantially concurrent assurance that sterilization has been achieved. The biological indicators were incubated for greater assurance that sterilization had been achieved.
The chemical indicators had the drawback that they only measured whether the desired result had been achieved after the process was complete. Because sterilization could take an extended period of time, valuable time could be lost if the process went awry, for example if the process was failing to maintain an adequate concentration of the sterilant vapor within the chamber. Accordingly, others proposed to replace or supplement the chemical indicators with parametric monitors which provided a real time indication of conditions inside the isolator. Typical parameters included temperature, humidity, pressure, and concentration of the gaseous sterilant. Because gaseous sterilant concentration sensors were relatively expensive, their use was limited, often to a single concentration sensor. The concentration sensor could be packaged like the items to be sterilized, positioned in the single location that was deemed most difficult to sterilize, or positioned at the outlet of the chamber or isolator. By monitoring the parametric conditions inside the isolator, the introduction of sterilant vapor could be controlled such that previously selected sterilization parameters were met, particularly a combination of time, temperature, and concentration.
Rather than limiting the treatment area to a relatively small sterilization chamber or isolator, it has also been proposed to expand the size of the chamber to relatively large chambers. See, for example, U.S. Pat. No. 6,077,480. As the size of the chamber was expanded, it became convenient to use multiple sources of the decontaminant vapor and multiple sensors for sensing concentration and other parametric conditions.
The larger enclosure can be as large as a room of a building, the interior of an aircraft, or a warehouse which contains items to be decontaminated. When decontaminating whole rooms and their contents or using warehouses as the decontamination chamber, the gaseous sterilant can be supplied from the exterior, possibly through the HVAC system, or from a portable vapor source that is moved into the room. Conversely, it has been proposed to use a single vapor source to decontaminate adjacent rooms.
Vapor decontaminants, such as hydrogen peroxide vapor, have been found to be effective for deactivating (render non-toxic or less toxic to humans) various chemical weapons, such as various types of nerve gas as well as for deactivating biological agents, such as pathogenic organisms.
The prior systems have been successful in large but limited to spaces that could be treated as one or a series of individual discrete environmental regions. The present application now approaches the problem of larger more convoluted interior spaces such as airport terminal concourses, office buildings with open interior architectural designs, and the like in which treatment regions flow together.
The present invention provides a new and improved decontamination technique and apparatus which overcomes the above-referenced problems and others.